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A117081 a(n) = 36*n^2 - 810*n + 2753, producing the conjectured record number of 45 primes in a contiguous range of n for quadratic polynomials, i.e., abs(a(n)) is prime for 0 <= n < 44. 5

%I

%S 2753,1979,1277,647,89,-397,-811,-1153,-1423,-1621,-1747,-1801,-1783,

%T -1693,-1531,-1297,-991,-613,-163,359,953,1619,2357,3167,4049,5003,

%U 6029,7127,8297,9539,10853,12239,13697,15227,16829,18503,20249,22067,23957,25919,27953,30059,32237,34487,36809,39203,41669

%N a(n) = 36*n^2 - 810*n + 2753, producing the conjectured record number of 45 primes in a contiguous range of n for quadratic polynomials, i.e., abs(a(n)) is prime for 0 <= n < 44.

%C The absolute values of a(n) for 0 <= n <= 44 are primes, a(45) = 39203 = 197*199. The positive prime terms are in A050268.

%C The polynomial is a transformed version of the polynomial P(x) = 36*x^2 + 18*x - 1801 whose absolute value gives 45 distinct primes for -33 <= x <= 11, found by Ruby in 1989. It is one of the 3 known polynomials whose absolute value produces more than 40 primes in a contiguous range of n. For the other two polynomials, which produce 43 primes, see A117081 and A267252. - _Hugo Pfoertner_, Dec 13 2019

%D Paulo Ribenboim, The Little Book of Bigger Primes, Second Edition, Springer-Verlag New York, 2004.

%H Vincenzo Librandi, <a href="/A117081/b117081.txt">Table of n, a(n) for n = 0..1000</a>

%H François Dress and Michel Olivier, <a href="https://projecteuclid.org/euclid.em/1047262355">Polynômes prenant des valeurs premières</a>, Experimental Mathematics, Volume 8, Issue 4 (1999), 319-338.

%H C. Rivera, <a href="http://www.primepuzzles.net/problems/prob_012.htm">Problem 12: Prime producing polynomials</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Prime-GeneratingPolynomial.html">Prime-Generating Polynomial</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).

%F G.f.: (2753-6280*x+3599*x^2)/(1-x)^3. [_Colin Barker_, May 10 2012]

%F a(0)=2753, a(1)=1979, a(2)=1277, a(n)=3*a(n-1)-3*a(n-2)+a(n-3). - _Harvey P. Dale_, Jun 20 2013

%t f[n_] := If[Mod[n, 2] == 1, 36*n^2 - 810*n + 2753, 36*n^2 - 810*n + 2753] a = Table[f[n], {n, 0, 100}]

%t CoefficientList[Series[(2753-6280*x+3599*x^2)/(1-x)^3,{x,0,50}],x] (* _Vincenzo Librandi_, May 12 2012 *)

%t Table[36n^2-810n+2753,{n,0,50}] (* or *) LinearRecurrence[{3,-3,1},{2753,1979,1277},50] (* _Harvey P. Dale_, Jun 20 2013 *)

%o (PARI) {for(n=0, 46, print1(36*n^2-810*n+2753, ","))}

%o (MAGMA) I:=[2753, 1979, 1277]; [n le 3 select I[n] else 3*Self(n-1)-3 *Self(n-2)+Self(n-3): n in [1..50]]; // _Vincenzo Librandi_, May 12 2012

%Y Cf. A005846, A050267, A050268, A117081, A267252.

%K sign,easy,less

%O 0,1

%A _Roger L. Bagula_, Apr 17 2006

%E Edited by _N. J. A. Sloane_, Apr 27 2007

%E Title extended by _Hugo Pfoertner_, Dec 13 2019

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Last modified April 16 17:01 EDT 2021. Contains 343050 sequences. (Running on oeis4.)